solution

A system consisting of 2 lb of water vapor, initially at 300F and occupying a volume of 20 ft3 , is compressed isothermally to a volume of 9.05 ft3 . The system is then heated at constant volume to a final pressure of 120 lbf/in.2 During the isothermal compression there is energy transfer by work of magnitude 90.8 Btu into the system. Kinetic and potential energy effects are negligible. Determine the heat transfer, in Btu, for each process.

A system consisting of 1 kg of H2O undergoes a power cycle composed of the following processes:

Process 1–2: Constant-pressure heating at 10 bar from saturated vapor.

Process 2–3: Constant-volume cooling to p3 5 bar, T3 160C.

Process 3–4: Isothermal compression with Q34 815.8 kJ.

Process 4–1: Constant-volume heating.

Sketch the cycle on T–v and p–v diagrams. Neglecting kinetic and potential energy effects, determine the thermal efficiency.